[Bug tree-optimization/100400] New: ICE in visit_loops_in_gang_single_region

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100400

            Bug ID: 100400
           Summary: ICE in visit_loops_in_gang_single_region
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: openacc
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

g++-12.0.0-alpha20210502 snapshot (g:92f59e47f5a468b96b12b15233a6729904b1a1ee)
ICEs when compiling the following testcase, reduced from
libgomp/testsuite/libgomp.oacc-c-c++-common/kernels-decompose-1.c, w/ -O1
-fopenacc -g --param openacc-kernels=decompose:

int *p;

void
foo (void)
{
#pragma acc kernels
  {
    int c;

    p = &c;

#pragma acc loop independent
    for (c = 0; c < 1; ++c)
      ;
  }
}

% g++-12.0.0 -O1 -fopenacc -g --param openacc-kernels=decompose -c uupipzvt.c
during GIMPLE pass: omp_oacc_kernels_decompose
uupipzvt.c: In function 'void foo()':
uupipzvt.c:14:7: internal compiler error: in visit_loops_in_gang_single_region,
at omp-oacc-kernels-decompose.cc:242
   14 |       ;
      |       ^
0x8b682a visit_loops_in_gang_single_region
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:242
0x8b682a visit_loops_in_gang_single_region
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:230
0xe16a2a walk_gimple_stmt(gimple_stmt_iterator*, tree_node*
(*)(gimple_stmt_iterator*, bool*, walk_stmt_info*), tree_node* (*)(tree_node**,
int*, void*), walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:578
0xe16c70 walk_gimple_seq_mod(gimple**, tree_node* (*)(gimple_stmt_iterator*,
bool*, walk_stmt_info*), tree_node* (*)(tree_node**, int*, void*),
walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:51
0xe16b39 walk_gimple_stmt(gimple_stmt_iterator*, tree_node*
(*)(gimple_stmt_iterator*, bool*, walk_stmt_info*), tree_node* (*)(tree_node**,
int*, void*), walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:641
0xe16c70 walk_gimple_seq_mod(gimple**, tree_node* (*)(gimple_stmt_iterator*,
bool*, walk_stmt_info*), tree_node* (*)(tree_node**, int*, void*),
walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:51
0xe16d03 walk_gimple_seq(gimple*, tree_node* (*)(gimple_stmt_iterator*, bool*,
walk_stmt_info*), tree_node* (*)(tree_node**, int*, void*), walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:81
0x1bf9048 make_loops_gang_single
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:290
0x1bf9048 make_region_seq
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:331
0x1bfb60c decompose_kernels_region_body
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:1336
0x1bfb60c omp_oacc_kernels_decompose_1
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:1453
0x1bfb60c omp_oacc_kernels_decompose_callback_stmt
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:1478
0xe16a2a walk_gimple_stmt(gimple_stmt_iterator*, tree_node*
(*)(gimple_stmt_iterator*, bool*, walk_stmt_info*), tree_node* (*)(tree_node**,
int*, void*), walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:578
0xe16c70 walk_gimple_seq_mod(gimple**, tree_node* (*)(gimple_stmt_iterator*,
bool*, walk_stmt_info*), tree_node* (*)(tree_node**, int*, void*),
walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:51
0xe16b15 walk_gimple_stmt(gimple_stmt_iterator*, tree_node*
(*)(gimple_stmt_iterator*, bool*, walk_stmt_info*), tree_node* (*)(tree_node**,
int*, void*), walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:685
0xe16c70 walk_gimple_seq_mod(gimple**, tree_node* (*)(gimple_stmt_iterator*,
bool*, walk_stmt_info*), tree_node* (*)(tree_node**, int*, void*),
walk_stmt_info*)
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/gimple-walk.c:51
0x1bf89d6 omp_oacc_kernels_decompose
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:1495
0x1bf89d6 execute
       
/var/tmp/portage/sys-devel/gcc-12.0.0_alpha20210502/work/gcc-12-20210502/gcc/omp-oacc-kernels-decompose.cc:1534